THE THEOET OE COMPOUND COLOUES. 
75 
Table IX. 
Observations by J., October 1859, 
( 24 .) 
( 44 .) 
( 68 .) 
44-3(20)= I8-I 
- 2-5 
+ 2-3 
16-0(28)= 18-1 
+ 6-2 
- 0-7 
21-5(32)= 18-1 
+ 25-2 
- 0-7 
19-3(36)= 8-1 
+27-5 
- 0-3 
20-7(40)= 2-1 
+27-5 
- 0-5 
52-3(48)=- 1-4 
+27-5 
+ 10-7 
95-0(52)=- 2-4 
+27-5 
+ 37-0 
51-7(56) = - 2-2 
+ 4-8 
+37-0 
37-2(60) = - 1-2 
+ 0-8 
+ 37-0 
36-7(64)=- 0-2 
+ 0-8 
+37-0 
35-0(72)=+ 0-6 
- 0-2 
+ 37-0 
40-0(76)=+ 0-9 
+ 0-5 
+37-0 
51-0(80)=+ 1-1 
+ 0-5 
+ 37-0 
§ XIII. Comparison of Results hy Newton’s Diagram. 
The relations of the colours, as given by these observations, are laid down in hg. 6, 
Plate I. It appears from this diagram, that the positions of the colours lie nearly in a 
straight line from (24) to (44), and from (48) to (60). The colours beyond (60) are 
crowded together, as in the other diagram, and the observations are not yet sufficiently 
accurate to distinguish their relative positions accurately. The colour (20) at the red 
end of the spectrum is further from the line joining (24) and (68) than in the other 
diagram, but I have not obtained satisfactoiy observations of these extreme colours. It 
will be observed that (32), (36), and (40) are placed further to the right in fig. 5 than in 
fig. 4, showing that the second observer (J.) sees more green in these colours than the first 
(K.), also that (48), (52), (56), and (60) are much further up in fig. 5, showing that to 
the second observer they appear more blue and less green. These differences were well 
seen in making an obseiwation. When the instrument was adjusted to suit the first 
observer (K.), then, if the selected colour were (32), (36), or (40), the second (J.), on 
looking into the instrument, saw it too green; but if (48), (52), (56), or (60) were the 
selected colour, then, if right to the first observer, it appeared too blue to the second. 
If the instrument were adjusted to suit the second observer, then, in the first case, the 
other saw red, and in the second green ; showing that there was a real difference in the 
eyes of these two indhiduals, producing constant and measurable difierences in the 
apparent colour of objects, 
§ XR'. Comparison by Curves of Intensity of tie Frimaries. 
Figs. 6 and 7, Plate I,, are intended to indicate the intensities of the three standard 
